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2002 gmc envoy_slt
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11 Posts
Discussion Starter · #1 ·
I have not noticed this until the last few weeks but, when I turn the engine of our '02 Envoy off, I hear a sound that is much like air pressure being suddenly released to atmosphere (though it could be a vacuum thing too, of course). The sound seems to be coming from somewhere below the driver's position but that may be in error because one ear of mine is partially plugged and direction sensing of sound is impaired. Can anyone help me figure out where this sound is coming from?

Thanks in advance.
 

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2004 gmc
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26,181 Posts
Very likely to be AC refrigerant gurgling as the pressure (from high to low) equalizes across the compressor when the engine's off.

To prove it, turn the AC off a few miles before you reach home, and see if it makes the same noise when you stop.
 

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2003 chevy trailblazer_ls
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5,268 Posts
It's actually the guages powering off...
I get this sound too... sound of small gears coming to rest.
this can be confirmed by listening to the sound and watching the needles as they park. More apparent in cold weather.
 

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2004 chevy trailblazer_lt
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44 Posts
I have the same sound too, I think all TVs have it. It sounds much like truck with air brakes discharging built up pressure... only almost a MINI level...
That is exactly what I thought when I first heard it. AC wasn't on either when this noise occurs. I would have never thought it was the gauges. Thanks for that.
 

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2006 chevy trailblazer_lt
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179 Posts
I guess in theory it could be your gauges on shutdown. My gauges do that to, it sounds more like a whoosing noise, than a "jet plane". Anyway, does it do that on startup aswell? If so, my best guess is that your stepper motor or motors are making that noise. You can replace them without a whole new dash, but you have to be extremely careful of the circuitry, and you need to be savvy at soildering. Best of luck, let us know what happens. Just to let you know these stepper motors are a common problem in trailvoys, so you are not the only one.
 
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